Structure-from-Motion photogrammetry as a tool for harvest residue pile measurement

Authors: Luke Riedinger, Campbell Harvey
Publication: New Zealand Journal of Forestry, Volume N.Z.J.For. 2020, Issue N.Z.J.For. 65(4) 2021, pp 6-11, Jan 2021
Publisher: New Zealand Institute of Forestry

Abstract: The issue of harvest residue management has been brought to the forefront of public knowledge after recent storms. Key to managing residue piles is the ability to measure them in a repeatable manner. This work aims to evaluate the method of Structure-from- Motion (SfM) photogrammetry for determining the bulk volume of piled harvest residues. A series of piles were photographed and reconstructed as Point Clouds and Digital Elevation Models (DEMs) using SfM for the measurement of bulk volume. True dimensions of the piles were well preserved in the models, with most models reproducing to within 0.1 m of actual dimensions. The DEMs, from which bulk volumes were determined, had resolutions ranging from 3.36 to 1.51 cm/pixel. The combination of these factors indicates that the volumes determined from the models were accurate representations of actual pile volumes. It is concluded that SfM photogrammetry is a reasonable method to be employed by harvest managers looking to determine the volume of piled forestry slash. Due to the time involved in processing the imagery, which ranges from 30 minutes to over three hours, it is likely that its use is targeted at high-risk residue piles or as a part of a residue monitoring study.